The supplemental inflatable restraint (SIR) system supplements the protection offered by the vehicle seat belt system. The SIR system has several inflater modules located throughout the vehicle. The inflatable restraint steering wheel module, inflatable restraint dash module in passenger side of dash, and the inflatable restraint side impact module - LF and RT. These can be located in the sides of the seat or inside side body trim. Each inflater module has a deployment circuit that is controlled by the inflatable restraint Sensing and Diagnostic Module (SDM), which is mounted inside of the vehicle, usually under the passenger side carpet.
The computer determines the severity of a collision with the assistance of various sensors and inputs. When the system detects a collision of sufficient force, it will process the information provided by the sensors to inflate the airbags. The SDM performs continuous diagnostic monitoring of the SIR system electrical components. Upon detection of a circuit malfunction, the SDM will set a diagnostic trouble code and inform the driver by commanding the instrument panel cluster (IPC) to turn the AIR BAG indicator ON. The steering column and knee bolster pads are designed to absorb energy during frontal collisions in order to limit leg movement and lessen the chance of injury to the driver or passengers legs.